Wednesday, 6 December 2017

Vibrational states of nano-confined water molecules in beryl investigated by first-principles calculations and optical experiments

Belyanchikov, Mikhail, Elena Zhukova, Sergei Tretiak, Andriy Zhugayevych, Martin Dressel, Frank Uhlig, Jens Smiatek, Maria Fyta, Victor G. Thomas, and Boris Gorshunov. "Vibrational states of nano-confined water molecules in beryl investigated by first principles calculations and optical experiments." Physical Chemistry Chemical Physics (2017).
Abstract
Using quantum mechanical calculations within density functional theory, we provide a comprehensive analysis of infrared-active excitation of water molecules confined in nanocages of a beryl crystal lattice. We calculate infrared-active modes including the translational, librational, and mixed-type resonances of regular and heavy water molecules. The results are compared to the experimental spectra measured for the two principal polarizations of the electric field: parallel and perpendicular to the crystallographic c-axis. Good agreement is achieved between calculated and measured isotopic shifts of the normal modes. We analyze the vibrational modes in connection with the structural characteristics and arrangements of water molecules within the beryl crystal. Specific atomic displacements are assigned to each experimentally detected vibrational mode resolving the properties of nano-confined water on scales not accessible by experiments. Our results elucidate the applicability and efficiency of a combined experimental and computational approach for describing and an in-depth understanding of nano-confined water, and pave the way for future studies of more complex systems.

Graphical abstract: Vibrational states of nano-confined water molecules in beryl investigated by first-principles calculations and optical experiments

... dielectric permittivity and optical conductivity were directly determined using quasioptical
spectrometer based on monochromatic and continuously frequency tunable radiation generators –
backward- wave oscillators 33 and a pulsed THz time-domain teraview TPS Spectra ...



for full paper see http://pubs.rsc.org/en/content/articlelanding/2017/cp/c7cp06472a/unauth#!divAbstract